A wide variety of known medical devices can be implanted within a patient's body to provide interventional or remedial treatments. Occlusion devices, for example, can be implanted to close perforations in septa. An atrial septal defect (ASD) in the heart is an abnormal opening in the septum between the left and right atria of the heart, and is one such condition that can be treated by implanting an occlusion device. A ventricular septal defect (VSD) in the heart is an abnormal opening in the septum between the left and right ventricles of the heart, and is another condition that can be treated by implanting an occlusion device.
Occlusion devices can also be implanted to block or occlude undesired conduits, fistulae, or ostia. For example, the left atrial appendage (LAA) is a closed cavity that looks like a small thumb or windsock, and is connected to the anterolateral wall of the left atrium between the mitral valve and the root of the left pulmonary vein. The LAA contracts with the left atrium during a normal heart cycle and keeps blood therein from becoming stagnant. However, with atrial fibrillation, the LAA often fails to contract with any vigor due to disorganized electrical signals. As a result, thrombi can be predisposed to form in the stagnant blood within the LAA. An implantable medical device can be used to block off the LAA to prevent an escape of thrombi from the LAA, preventing introduction of the thrombi to an individual's vasculature. Other types of known medical devices can be also implanted in patients to treat a wide variety of disorders.
Many implantable medical devices are delivered to a deployment site using minimally invasive transcatheter techniques. In such cases, the medical device is typically configured in a collapsed arrangement and delivered to the internal deployment site via a delivery sheath. At the deployment site, the medical device is ejected from the sheath and expands to a larger size to provide effective treatment of the particular medical condition, such as occluding an ASD, VSD, or LAA. In some cases, a delivery catheter is attached to the implantable medical device and is used to advance the collapsed implantable medical device through the delivery sheath to the deployment site.
One example delivery system attaches the delivery catheter to the implantable medical device via a threaded screw-type attachment. For example, the implantable medical device may include a female threaded receptacle that is configured to receive a male threaded portion of the delivery catheter, and the delivery catheter is attached to the medical device in this manner. After the implantable device is deployed from the delivery sheath at the deployment site, a clinician operator provides a rotational force at a proximal end of the delivery catheter to cause the delivery catheter to unscrew, and detach, from the implantable device.